\begin{figure}[H]
\begin{tikzpicture}
\tikzset{edge from parent/.style=
	{draw,
	 edge from parent path={(\tikzparentnode.south)
							-- +(0,-8pt)
							-| (\tikzchildnode)}}
}

\Tree [
.{\{pre\} encrypt mid; \\ decrypt mid \{post\}}
	[.\node[draw]{eapply hoare\_seq};
		[.{\{pre\} encrypt mid \{st$_k$\}}
			[.\node[draw]{unfold encrypt};
				[.\node[draw]{eapply hoare\_seq};
					[.{\{pre\} keyAddition mid k$_2$ \{st$_1$\}}
						\node[draw]{apply (hoare\_key\_addition k$_2$)};
					]
					[.{\{st$_1$\} nibbleSub ... \{st$_k$\}}
						[.{\{st$_1$\} nibbleSub \{st$_2$\}}
							\node[draw]{apply hoare\_nibble\_sub};
						]
						{\{st$_2$\} ... \{st$_k$\}}
					]
				]
			]
		]
		[.{\{st$_k$\} decrypt mid \{post\}}
			[.{\ldots}
				[.{\{st$_n$\} keyAddition mid k$_2$ \{post\}}
					\node[draw]{apply (hoare\_key\_addition k$_2$)};
				]
			]
		]
	]
]
\end{tikzpicture}
\caption{Árbol de prueba de hoare\_miniaes} \label{tree:hoare_miniaes}
\end{figure}